1. Field of the Invention
Embodiments of the invention relate generally to the field of high thermal conductivity arrays of nanotubes. More particularly, an embodiment of the invention relates to fabrication of high thermal conductivity arrays of carbon nanotubes and their composites.
2. Discussion of the Related Art
Thermal management of microelectronic packages is an ever-increasing problem as chip sizes become smaller and more densely packed with transistors. Conventional thermal interface materials (TIMs) are losing the ability to carry the corresponding heat from integrated circuits (ICs) to their cooling fins. Carbon nanotubes with their high thermal conductivities have been envisioned as an enabling technology to provide this heat pathway. FIG. 10 depicts a comparison of thermal conductivities of carbon-based materials and other materials. However, although individual nanotubes exhibit sufficiently high thermal conductivities, assemblies of nanotubes in the forms of fibers, papers, and other composites do not. A single single-walled carbon nanotube (SWNT) exhibits highly directional thermal conductivity of 3000 W/mK along its axis (Dresselhaus, 1985) while a fiber of bundled SWNTs exhibits only 20 W/mK (see FIG. 10). Although SWNTs and multiwall carbon nanotubes (MWNTs) can be assembled into papers, fibers, and other aggregated forms, these aggregated forms are not optimally assembled for high thermal conductivity. In the past, processing nanotubes has invariably resulted in their aggregation. When nanotubes touch one another and heat is required to hop from one nanotube to another, high thermal diffusivities and directional properties are lost.
The problems that need to be solved are i) microelectronic package thermal management, ii) thermal interface materials that posses sufficiently high heat carrying capacity and iii) nanotubes that are optimally assembled without aggregation. What is needed is a solution that simultaneously solves all of these problems.